Wedge ramp distractor and related methods for use in implanting artificial intervertebral discs

ABSTRACT

Instruments and methods for distracting an intervertebral space and inserting and impacting artificial intervertebral discs. A wedge distractor employing opposing ramps through which an inserter/impactor holding an artificial intervertebral disc is admitted, the passage of which through the distractor results in distraction of the intervertebral space simultaneous with insertion of the artificial intervertebral disc. A method of distracting an intervertebral space comprising the steps of inserting a distractor having opposing ramped surfaces into an intervertebral space and inserting an inserter/impactor holding an artificial intervertebral disc between the opposing ramped surfaces of the distractor to insert/impact the artificial intervertebral disc in the intervertebral space. A system for distracting an intervertebral space employing a wedge distractor, inserter/impactor and artificial intervertebral implant.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation-in-part application ofU.S. patent application Ser. No. 10/425,267 (filed Apr. 29, 2003)entitled “Wedge Plate Inserter/Impactor and Related Methods for Use inImplanting an Artificial Intervertebral Disc”, which is a continuingapplication of U.S. patent application Ser. No. 10/282,356 (filed Oct.29,2002) entitled “Instrumentation and Methods For Use In Implanting anArtificial Intervertebral Disc”, which is a continuing application ofU.S. patent application Ser. No. 10/256,160 (filed Sep. 26, 2002)entitled “Artificial Intervertebral Disc Having Limited Rotation Using aCaptured Ball and Socket Joint With a Solid Ball and Compression LockingPost”, which is a continuing application of U.S. patent application Ser.No. 10/175,417 (filed Jun. 19, 2002) entitled “Artificial IntervertebralDisc Utilizing a Ball Joint Coupling”, which is a continuing applicationof U.S. patent application Ser. No. 10/151,280 (filed May 20, 2002)entitled “Tension Bearing Artificial Disc Providing a Centroid of MotionCentrally Located Within an Intervertebral Space”, which is a continuingapplication of both U.S. patent application Ser. No. 09/970,479 (filedOct. 4, 2001) entitled “Intervertebral Spacer Device Utilizing aSpirally Slotted Belleville Washer Having Radially Extending Grooves” aswell as U.S. patent application Ser. No. 10/140,153 (filed May 7, 2002)entitled “Artificial Intervertebral Disc Having a Flexible Wire MeshVertebral Body Contact Element”, the former being a continuingapplication of U.S. patent application Ser. No. 09/968,046 (filed Oct.1, 2001) entitled “Intervertebral Spacer Device Utilizing a BellevilleWasher Having Radially Extending Grooves” and the latter being acontinuing application of both U.S. patent application Ser. No.09/970,479 (detailed above) as well as U.S. patent application Ser. No.10/128,619 (filed Apr. 23, 2002) entitled “Intervertebral Spacer Havinga Flexible Wire Mesh Vertebral Body Contact Element”, which is acontinuing application of both U.S. patent application Ser. No.09/906,119 (filed Jul. 16, 2001) and entitled “Trial IntervertebralDistraction Spacers” as well as U.S. patent application Ser. No.09/982,148 (filed Oct. 18, 2001) and entitled “Intervertebral SpacerDevice Having Arch Shaped Spring Elements”. All of the above mentionedapplications are hereby incorporated by reference herein in theirrespective entireties.

FIELD OF THE INVENTION

[0002] This invention relates generally to systems and methods for usein spine arthroplasty, and more specifically to instruments fordistracting an intervertebral space and inserting and impactingartificial intervertebral discs, and methods of use thereof.

BACKGROUND OF THE INVENTION

[0003] The bones and connective tissue of an adult human spinal columnconsists of more than twenty discrete bones coupled sequentially to oneanother by a tri-joint complex that consists of an anterior disc and thetwo posterior facet joints, the anterior discs of adjacent bones beingcushioned by cartilage spacers referred to as intervertebral discs.These more than twenty bones are anatomically categorized as beingmembers of one of four classifications: cervical, thoracic, lumbar, orsacral. The cervical portion of the spine, which comprises the top ofthe spine, up to the base of the skull, includes the first sevenvertebrae. The intermediate twelve bones are the thoracic vertebrae, andconnect to the lower spine comprising the five lumbar vertebrae. Thebase of the spine is the sacral bones (including the coccyx). Thecomponent bones of the cervical spine are generally smaller than thoseof the thoracic spine, which are in turn smaller than those of thelumbar region. The sacral region connects laterally to the pelvis. Whilethe sacral region is an integral part of the spine, for the purposes offusion surgeries and for this disclosure, the word spine shall referonly to the cervical, thoracic, and lumbar regions.

[0004] The spinal column is highly complex in that it includes thesemore than twenty bones coupled to one another, housing and protectingcritical elements of the nervous system having innumerable peripheralnerves and circulatory bodies in close proximity. In spite of thesecomplications, the spine is a highly flexible structure, capable of ahigh degree of curvature and twist in nearly every direction.

[0005] Genetic or developmental irregularities, trauma, chronic stress,tumors, and degenerative wear are a few of the causes that can result inspinal pathologies for which surgical intervention may be necessary.With respect to the failure of the intervertebral disc, and theinsertion of implants and/or height restorative devices, several methodsand devices have been disclosed in the prior art that achieveimmobilization and/or fusion of adjacent bones by implanting artificialassemblies in or on the spinal column. More recently, the development ofnon-fusion implant devices, which purport to permit continued naturalmovement in the tri-joint complex, have provided great promise as apreferably alternative to fusion devices. The region of the back thatneeds to be corrected, as well as the individual variations in anatomy,determine the appropriate surgical protocol and implantation assembly.Generally, the preparation of the intervertebral space for the receiptof fusion or non-fusion devices involves removing the damaged discmaterial and thereafter distracting the adjacent vertebral bones totheir appropriate distance apart. Once the proper height of theintervertebral space is restored, the fusion or non-fusion device can beimplanted.

[0006] It is an object of the invention to provide instrumentation andmethods that enable surgeons to more accurately, easily, and efficientlyimplant fusion or non-fusion devices. Other objects of the invention notexplicitly stated will be set forth and will be more clearly understoodin conjunction with the descriptions of the preferred embodimentsdisclosed hereafter.

SUMMARY OF THE INVENTION

[0007] The preceding objects are achieved by the invention, whichincludes, among other aspects, an inserter/impactor (sometimes referredto herein as an “inserter/impactor”) useful for holding and manipulatingartificial intervertebral discs, a wedge-ramp distractor, and a parallelinsertion distractor, the latter two items being useful for distractingan intervertebral space and inserting an artificial intervertebral disctherein.

[0008] More particularly, the systems and methods disclosed herein areintended for use in spine arthroplasty procedures, and specifically foruse with the systems and methods described herein in conjunction withthe systems and methods in conjunction with the systems and methodsdescribed in U.S. patent application Ser. No. 10/282,356 (filed Oct. 29,2002) entitled “Instrumentation and Methods For Use In Implanting anArtificial Intervertebral Disc” (hereinafter referred to as “the '356application”) as well as U.S. patent application Ser. No. 10/256,160(filed Sep. 26, 2002) entitled “Artificial Intervertebral Disc HavingLimited Rotation Using a Captured Ball and Socket joint With a SolidBall and Compression Locking Post” (hereinafter referred to as “the '160application”) as well as U.S. patent application Ser. No. 09/906,127(filed Jul. 16, 2001) entitled “Insertion Tool For Use WithIntervertebral Spacers”, the entirety of which is incorporated byreference herein (hereinafter referred to as “the '127 application”).However, it should be understood that the systems and methods describedherein are also suitable for use with other systems and methods withoutdeparting from the scope of the invention.

[0009] While the instrumentation described herein (e.g., theinserter/impactors and distractors) will be discussed for use with theartificial intervertebral disc of FIGS. 1g-n of the '356 application(hereinafter, such figures will merely be referred to as “FIGS. 1g-n”),such discussions are merely by way of example and not intended to belimiting of their uses. Thus, it should be understood that theinstrumentation and methods can be used with any of the artificialintervertebral discs disclosed in the '356 or '160 applications, or anyother artificial intervertebral disc having (or being modifiable ormodified to have) suitable features therefor. Moreover, it isanticipated that the features of the artificial intervertebral discs(e.g., plate surfaces, engagement holes, and baseplate teeth) that areused by the inserter/impactors and distractors discussed herein to holdand/or manipulate the artificial intervertebral disc can be applied,individually, or collectively or in various combinations, to othertrials, spacers, artificial intervertebral discs, or other orthopedicdevices as stand-alone innovative features for enabling such trials,spacers, artificial intervertebral discs, or other orthopedic devices tobe more efficiently and more effectively held and/or manipulated by theinserter/impactors and/or distractors described herein or by toolshaving suitable features. In addition, it should be understood that theinvention encompasses instrumentation and methods for implantingartificial intervertebral discs, spacers, trials (static or dynamic),and/or other orthopedic devices, that have one or more of the featuresdisclosed herein, in any combination, and that the invention istherefore not limited to artificial intervertebral discs, spacers,trials, and/or other orthopedic devices having all of the featuressimultaneously.

[0010] Preferably, with regards to each artificial intervertebral discto be implanted, a plurality of sizes of the artificial intervertebraldisc would be available (e.g., the artificial intervertebral disc 160 ofFIGS. 1g-n). That is, preferably, a plurality of the same type ofartificial intervertebral disc would be available, each of the pluralityhaving a respective width and depth dimension combination that allows itto fit within a correspondingly dimensioned intervertebral space. Forexample, the plurality of artificial intervertebral discs could includeartificial intervertebral discs having widths being either 35 mm or 40mm, and depths ranging from 14 mm to 18 mm in 1 mm increments, for atotal of 10 discs. It should be understood that the artificialintervertebral discs can be offered in a variety of dimensions withoutdeparting from the scope of the invention, and that the dimensionsspecifically identified and quantified herein are merely exemplary. Eachof the plurality of artificial intevertebral discs preferably furtherincludes features that can be used by the inserter/impactors (describedbelow) and/or the wedge-ramp and parallel insertion distractors(described below) and/or the inserter/impactor or other instrumentsdescribed in the '356 application.

[0011] With regard to features that can be used by theinserter/impactors described here and in the '356 application, eachartificial intervertebral disc includes an anteriorly facing flatsurface, flanked by two anteriolaterally facing flat surfaces (one oneach side of the anteriorly facing flat surface), and, to provide forholding of the disc for an anterior insertion approach, a hole spacedfrom the anteriorly facing flat surface, the hole having a longitudinalaxis parallel to the anteriorly facing flat surface. The holding pin ofthe inserter/impactor fits within the hole, and the angled flat surfacesof the disc fit against the correspondingly angled flat surfaces of theinserter/impactor, and operation of the inserter/impactor pulls theholding pin toward the flat surface of the inserter/impactor oppositethe pin, to rigidly hold the disc by the lower baseplate. The holdingpin protrudes from the wedge-shaped extended surface of the distal endof the inserter/impactor and is restricted from upward movement withrespect to the distal head by the presence of the wedge-shaped extendedsurface of the distal end of the inserter/impactor. More particularly,with any attempted upward movement of the holding pin, the pinencounters the upper surface of the channel in which the pin travels,preventing any such upward movement. When the intervertebral disc isheld in this manner, rotation of the disc about a longitudinal axisrelative to the inserter/impactor is prevented by interference of thecorners of the disc's flat surfaces and the corners of theinserter/impactor's flat surfaces, similar to the manner in which awrench holding a nut prevents rotation of the nut relative to thewrench. Further, when the disc is held in this manner, rotation of thedisc about a lateral axis of the disc relative to the inserter/impactoris prevented by interference of the inwardly facing surface of the firstbaseplate (e.g., upper baseplate) of the disc and the correspondingsurface (e.g., upper surface) of the wedge on the distal end, and byinterference of the inwardly facing surface of the second baseplate(e.g., lower baseplate) of the disc and the correspoding surface (e.g.,lower surface) of the wedge on the distal end. It is preferable that thewedge on the inserter/impactor will interfere between the first andsecond baseplates (e.g., upper and lower) so that the surfaces of thefirst and second baseplates align at a preferred 15 degrees angle oflordosis when the disc is held by the inserter/impactor.

[0012] Preferably, in order to provide for a holding of the disc for twoadditional (here, anteriolateral) insertion approaches, each disc alsoinclude two additional holes, one spaced apart from one of theanteriolaterally facing flat surfaces, and the other spaced apart fromthe other of the anteriolaterally facing flat surfaces. Accordingly,operation of the inserter/impactor can fit the holding pin into eitherof these two additional holes, and hold the anteriolaterally facing flatsurface (the one associated with the hole into which the pin is fit) ofthe disc against the flat surface of the inserter/impactor opposite thepin. It should be understood that preferably, in order to facilitatethese two additional approaches, the angle separating the anteriorlyfacing flat surface of the disc and one of the anteriolaterally facingflat surfaces of the disc is equal to the angle separating theanteriorly facing flat surface and the other of the anteriolaterallyfacing flat surfaces.

[0013] With regard to features that can be used by the wedge-rampdistractor and the parallel insertion distractor of the presentinvention, each artificial intervertebral disc includes fixation teethon the outwardly facing surface of the baseplate. Preferably, to permitthem to ride in the grooves of the wedge-ramp distractor, two sets ofteeth straddle the convex dome on the outwardly facing surface of eachbaseplate, and the teeth in each set are in straight rows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIGS. 1g-n of the '356 application show front (FIG. 1g), sidecutaway (FIG. 1h), top (FIG. 1i), perspective cutaway (FIG. 1j), bottomcutaway (FIG. 1k), top cutaway (FIG. 1l), bottom perspective (FIG. 1m),and top perspective (FIG. 1n) views of an exemplary artificialintervertebral disc for use with the present invention.

[0015]FIGS. 2a-c show side (FIG. 2a), perspective (FIG. 2b), andclose-up perspective (FIG. 2c) views of a wedge plate inserter/impactorof the present invention.

[0016]FIGS. 3a-d show bottom (FIG. 3a), side (FIG. 3b), top (FIG. 3c),and side cutaway (FIG. 3d) views of a distal end of a wedge plateinserter/impactor of the present invention.

[0017]FIGS. 4a-b show top (FIG. 4a) and side (FIG. 4b) views of a wedgeplate inserter/impactor of the present invention holding an exemplaryartificial intervertebral disc.

[0018]FIGS. 4c-e show top (FIG. 4c), side (FIG. 4d), and side cutaway(FIG. 4e) views of a distal end of a wedge plate inserter/impactor ofthe present invention holding an exemplary artificial intervertebraldisc.

[0019]FIG. 5 shows a close-up perspective view of a preferred embodimentof the distal end of a wedge plate inserter/impactor of the presentinvention.

[0020]FIG. 6 shows a close-up perspective view of the distal end of awedge plate inserter/impactor of the present invention according to FIG.5 holding an exemplary artificial intervertebral disc.

[0021]FIG. 7 shows a perspective view of a wedge ramp distractor of thepresent invention.

[0022]FIG. 8 shows a perspective view of the wedge ramp distractor ofthe present invention according to FIG. 7 in disassembled form.

[0023]FIG. 9 shows a perspective view of the wedge ramp distractor ofthe present invention according to FIG. 7 having inserted therein thewedge plate inserter/impactor of the present invention according to FIG.5 holding an exemplary artificial intervertebral disc.

[0024]FIG. 10 shows a perspective view of a parallel insertiondistractor of the present invention in disassembled form.

[0025]FIG. 11 shows a perspective view of a parallel insertiondistractor of the present invention holding an exemplary artificialintervertebral disc.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] While the invention will be described more fully hereinafter withreference to the accompanying drawings, it is to be understood at theoutset that persons skilled in the art may modify the invention hereindescribed while achieving the functions and results of the invention.Accordingly, the descriptions that follow are to be understood asillustrative and exemplary of specific structures, aspects and featureswithin the broad scope of the invention and not as limiting of suchbroad scope. Like numbers refer to similar features of like elementsthroughout.

[0027] A preferred embodiment of an artificial intervertebral disc(e.g., artificial intervertebral disc 160) for use with theinstrumentation of the present invention is referenced and described inthe '356 application, and the same description is hereby incorporated byreference herein. The artificial intervertebral disc illustrated inFIGS. 1g-n of the '356 application is discussed herein with reference tosuch figures, as an example of an artificial intervertebral discsuitable for use with the present invention.

[0028] A preferred embodiment of a wedge plate inserter/impactor of thepresent invention will now be described.

[0029] Referring now to FIGS. 2a-4 e, FIGS. 2a-c side (FIG. 2a),perspective (FIG. 2b), and close-up perspective (FIG. 2c), andperspective (FIG. 4d) views of a wedge plate inserter/impactor of thepresent invention. FIGS. 3a-d show bottom (FIG. 3a), side (FIG. 3b), top(FIG. 3c), and side cutaway (FIG. 3d) views of a distal end of a wedgeplate inserter/impactor of the present invention. FIGS. 4a-b show top(FIG. 4a) and side (FIG. 4b) views of a wedge plate inserter/impactor ofthe present invention holding an exemplary artificial intervertebraldisc. FIGS. 4c-e show top (FIG. 4c), side (FIG. 4d), and side cutaway(FIG. 4e) views of a distal end of a wedge plate inserter/impactor ofthe present invention holding an exemplary artificial intervertebraldisc.

[0030] It should be understood that the illustration and referenceherein to the artificial intervertebral disc shown in FIGS. 1g-n of the'356 application is merely to show an example of one type of artificialintervertebral disc that is contemplated by, encompassed by, andsuitable for use with, the present invention, and that such illustrationand reference herein is not meant to limit the scope of the presentinvention or limit the uses of the present invention. Rather, any otherartificial intervertebral disc (or any other orthopedic device) havingsuitable features for being used with the instrumentation and methodsdescribed herein are contemplated by the present invention. Indeed, thefeatures suitable for manipulation (e.g., angled flat surfaces withadjacent holes and/or opposing notches, and/or inwardly facing baseplatesurfaces) are encompassed by the present invention, regardless of towhat orthopedic device they may be applied. Other exemplary suitableartificial intervertebral discs include, but are not limited to, theartificial intervertebral discs described in the '160 application withregard to FIGS. 8a-y, 9 a-t, 10 a-t, 11 a-j, and 12 a-o thereof and bythe accompanying descriptions therefor (e.g., embodiments identified asthe first, second, third, fourth, and fifth preferred embodiments of thefourth embodiment family, etc.). It should be noted that, as can be seenfrom FIGS. 1g-n of the '356 application, that the artificialintervertebral disc shown in FIGS. 1g-n of the '356 application hasfeatures similar to those of these other suitable artificialintervertebral discs of the '160 application, and it should beunderstood that such similar features are structurally and functionallyas described in the '160 application. Such similar features include aninwardly facing surface of the upper baseplate, and a convex structureon the lower baseplate, the convex structure having an inwardly facingsurface.

[0031] And, while the instrumentation described herein (e.g., theinserter/impactor) as well as the instrumentation described in the '356application (e.g., the inserter/impactor described therein) will bediscussed for use with the artificial intervertebral disc of FIGS. 1g-nof the '356 application, such discussions are merely by way of exampleand not intended to be limiting of their uses. Thus, it should beunderstood that the tools can be used with any of the artificialintervertebral discs disclosed in the '356 application or the '160application, or any other artificial intervertebral disc having (orbeing modifiable or modified to have) suitable features therefor.Moreover, it is anticipated that the features of the artificialintervertebral disc (e.g., the angled flat surfaces and the inwardlyfacing baseplate surfaces, and accompanying holes) that are used by thetool discussed herein (or in the '356 application) to hold and/ormanipulate these devices (certain features, it should be noted, werefirst shown and disclosed in the '160 application, the '127 application,and/or the '356 application) can be applied, individually orcollectively or in various combinations, to other trials, spacers,artificial intervertebral discs or other orthopedic devices asstand-alone innovative features for enabling such trials, spacers,artificial intervertebral discs, or other orthopedic devices to be moreefficiently and more effectively held and/or manipulated by the toolsdescribed herein (or in the '356 application) or by other tools havingsuitable features. In addition, it should be understood that theinvention encompasses artificial intervertebral discs, spacers, trials(static or dynamic), and/or other orthopedic devices, that have one ormore of the features disclosed herein (or in the '356 application), inany combination, and that the invention is therefore not limited toartificial intervertebral discs, spacers, trials, and/or otherorthopedic devices having all of the features simultaneously.

[0032] Preferably, for each artificial intervertebral disc to beimplanted, a plurality of sizes of the artificial intervertebral discwould be available. That is, preferably, a plurality of the same type ofartificial intervertebral disc would be available, each of the pluralityhaving a respective width and depth dimension combination that allows itto fit within a correspondingly dimensioned intervertebral space. Forexample, the plurality of artificial intervertebral discs could includeartificial intervertebral discs having widths being either 35 mm or 40mm, and depths ranging from 14 mm to 18 mm in 1 m increments, for atotal of 10 discs.

[0033] The inserter/impactor 4000 is provided primarily for holding,inserting, repositioning, removing, impacting, extracting, and otherwisemanipulating an artificial intervertebral disc having features suitablefor being manipulated by the inserter/impactor. (However, it can also beused to hold, insert, reposition, remove, impact, extract, and otherwisemanipulate any other orthopedic device having suitable featurestherefor. For example, it should be understood that distraction of anintervertebral space can be accomplished in conjunction with acooperating tool or spacer that can be gripped by theinserter/impactor.) Exemplary suitable artificial intervertebral discsinclude, but are not limited to, the artificial intervertebral disc 160described herein and the artificial intervertebral discs described inthe '160 application with regard to FIGS. 8a-y, 9 a-t, 10 a-t, 11 a-j,and 12 a-o thereof and by the accompanying descriptions therefor (e.g.,embodiments identified as the first, second, third, fourth, and fifthpreferred embodiments of the fourth embodiment family, etc.). Regardingthe features suitable for being manipulated by the inserter/impactor4000, such features include those discussed above as being suitablefeatures on the disc 160, namely, an anteriorly facing flat surface onthe second (e.g., lower) baseplate of the trial or disc, flanked by twoanteriolaterally facing flat surfaces (one on each side of theanteriorly facing flat surface), and, to provide for holding of thetrial or disc for an anterior insertion approach, a hole spaced from theanteriorly facing flat surface, the hole having a longitudinal axisparallel to the anteriorly facing flat surface. Further regarding thefeatures suitable for being manipulated by the inserter/impactor, suchfeatures further include the inwardly facing surfaces of the baseplatesof the disc.

[0034] More particularly, the inserter/impactor 4000 includes a shaft4020 having a distal end 4040 that has angled flat surfaces 4200 a-ccorresponding to and fittable against angled flat surfaces of theartificial intervertebral disc (e.g., the surfaces 180 a-c of theartificial intervertebral disc 160) to be implanted. The distal end 4040has angled flat surfaces 4200 d-f corresponding to and fittable againstangled flat surfaces of the artificial intervertebral disc (e.g., thesurfaces 180 d-f of the artificial intervertebral disc 160) to beimplanted. The distal end 4040 has a wedge-shaped extension 4042including upper 4200 g and lower 4200 h wedge surfaces corresponding toand fittable against the inwardly facing surfaces of the artificialintervertebral disc (e.g., the lower surface 164 a of the upperbaseplate 168 a of the disc 160, and the upper surface 164 b of thelower baseplate 168 b of the disc 160, respectively) to be implanted.For example, in an anterior approach for the disc 160 (as shown in FIGS.4a-e), 180 a and 180 d facing 4200 a and 4200 d, 180 b and 180 e facing4200 b and 4200 e, 180 c and 180 f facing 4200 c and 4200 f, and 164 afacing 4200 g and 164 b facing 4200 h.

[0035] The inserter/impactor 4000 holds the disc 160 in a preferredposition with respect to the inserter/impactor 4000. (It should beunderstood that the surfaces of the wedge-shaped extension 4042 can bemodified within the scope of the present invention to hold the disc 160(or another orthopedic device) at positions other than those illustratedherein.) In the illustrated embodiment of the inserter/impactor 4000 inuse with the disc 160, the preferred position is with the baseplates 168a,b of the disc 160 angled at 15 degrees of lordosis with respect to oneanother. More particularly, preferably, the upper and lower surfaces(e.g., 4200 g and 4200 h) of the wedge-shaped extension 4042 protrudefrom the distal end 4040 and are formed to hold the baseplates 168 a,bsuch that they are angled at 15 degrees of lordosis with respect to oneanother. A surface (e.g., lower surface 4200 h) of the wedge-shapeextension 4042 that mates with an inwardly facing surface of a baseplate(e.g., the lower baseplate 168 b) of a disc (e.g., 160) may becorrespondingly shaped (e.g., curved or flat) for interaction or matingwith the disc baseplate (e.g., the lower surface 4200 h of thewedge-shaped extension as illustrated is curved to accommodate thesurface of the shield of the disc). Preferably, the forward surface 4200i of the wedge-shaped extension 4042 has a concave curvature towards theshaft 4020 of the inserter/impactor 4000, also for accommodating thecurvature of the surface of the shield of the disc.

[0036] Also preferably with regard to the preferred positioning, thewedge surfaces of the distal end 4040 protrude from a distance midwaywith respect to the top and bottom of the distal end 4040 and span(e.g., right to left or vice-versa) the entire distal face of the distalend 4040, and the surfaces 4200 d-f above the wedge on the distal end4040 are respectively perpendicular to the wedge's upper surface 4200 gsuch that each is disposed in parallel with its respective correspondingsurface of the disc 160 when the disc 160 is held by theinserter/impactor 4000 at the appropriate lordosis angle. (And,accordingly, are angled approximately 15 degrees with respect to thesurfaces below the wedge 4200 a-c.) Preferably, for an anteriorapproach, the wedge-shaped extension 4042 is designed and shaped to fitwith its antero-lateral confronting surfaces (4200 d,f and 4200 a,c)tightly against the correspondingly antero-laterally facing surfaces(180 d,f and 180 a,c) of the disc 160, but such that its anteriorconfronting surfaces (4200 e and 4200 b) are slightly spaced from theanteriorly facing surfaces (180 d and 180 b) of the disc 160, when thedisc is held by the inserter/impactor 4000. This is primarily to addressmanufacturing issues (in some cases, tolerances may not be adequatelydefined to ensure that all of those surfaces fit tightly against theircorresponding surfaces), so that if there are manufacturing anomalies,any slight tolerance differences that may exist are nevertheless stilladequate to ensure at least the tight fitting of the antero-lateralconfronting surfaces, so that manipulation of the disc 160 is possible(e.g., in the manner of a wrench against an angled nut). This can beachieved, e.g., by designing the anterior confronting surfaces (4200 eand 4200 b) to each be slightly greater in length than the correspondinganteriorly facing surfaces (180 e and 180 b) of the disc baseplates,while still being angled with respect to the antero-lateral confrontingsurfaces (4200 d,f and 4200 a,c) at the same angle the antero-laterallyfacing surfaces (180 d,f and 180 a,c) of the disc baseplates are angledwith respect to the anteriorly facing surfaces (180 e and 180 b) of thedisc. The increased length of the anterior confronting surfaces on thewedge extension results in the slight clearance between the anteriorlyfacing surfaces (180 e and 180 b) of the disc and the correspondinganterior confronting surface (4200 e and 4200 b) of the wedged distalend, thereby ensuring that the disc will be fully seated against theantero-lateral confronting surfaces of the distal end despite possiblemanufacturing, material or other inevitable variations in tolerances ofthe artificial intervertebral disc or the inserter/impactor. As notedabove, similar in this regard to the manner in which a wrench engages anut, this fitting increases the mechanical advantage towardrepositioning the disc in the intervertebral space. It should be noted,inasmuch as the inserter/impactor 4000 described herein can engage thedisc from the antero-lateral angles as well, the anterior confrontingsurfaces (4200 e and 4200 b) should also be longer than theantero-laterally facing surfaces (180 d,f and 180 a,c) of the disc, sothat a similar fitting occurs when the disc is held from theantero-lateral angles. Stated broadly, the primary confronting surfaces(e.g., the anterior confronting surfaces) of the inserter/impactor arepreferably slightly longer than the primary confronted surfaces (e.g.,anteriorly facing surfaces) of the disc for any given holdingorientation.

[0037] Further, the inserter/impactor 4000 includes a holding pin 4080that extends from the wedge 4042 along a longitudinal axis of the shaft4020, the pin 4080 having a distal end 4100 that is bent downwardly. Theholding pin 4080 is spring loaded (e.g., by a spring 4090) in a centralchannel of the shaft 4020, so that it is biased toward the shaft 4020(preferably, the bent end 4100 of the pin 4080 prevents it from enteringthe central channel). The holding pin 4080 is restricted from upwardlylateral movement with respect to the distal end of the inserter/impactorby the presence of the wedge-shaped extension 4042 of the distal end4040 of the inserter/impactor 4000. More particularly, with anyattempted upward movement of the holding pin 4080, the pin encountersthe upper surface of the channel in which the pin 4080 travels,preventing any such upward movement. The holding pin 4080 is preferablyheat treated (e.g., cold formed) to increase material quality (e.g.,strength).

[0038] A flange 4110, mechanically connected to the pin 4080 andtranslating adjacent the shaft 4020, can be pushed distally to overcomethe bias of the spring 4090 to space the pin 4080 away from the wedge4042. (An alternative configuration is one in which the flange 4110 andthe pin 4080 are formed from a single piece, rather than beingmechanically connected.) In this extended position, the pin 4080 can beinserted in a hole (e.g., 182 b) in the baseplate (e.g., 168 b) of theartificial intervertebral disc (e.g., 160). Releasing the flange 4110allows the spring 4090 to pull the pin 4080 back, causing the anteriorlyfacing surface 180 b of the baseplate 168 b to be held against the lowercentral flat surface 4200 b of the inserter/impactor 4000 and theanterioloaterally facing flat surfaces 180 a,c of the artificialintervertebral disc 160 to be held against the other corresponding flatsurfaces 4200 a,c of the inserter/impactor 4000. This can be furtherunderstood in light of the description of the manner in which theinserter/impactor of the '160 application functions to grip anorthopedic device, which is included in the '160 application andincorporated by reference herein. Simultaneously, the anteriorly facingsurface 180 e of the baseplate 168 a is pulled against the upper centralflat surface 4200 e of the inserter/impactor 4000 and theanterioloaterally facing flat surfaces 180 d,f of the artificialintervertebral disc 160 is pulled against the other corresponding flatsurfaces 4200 d,f of the inserter/impactor 4000. Additionally, the upperand lower wedge surfaces (4200 g,h) interfere between the inwardlyfacing surfaces 164 a,b of the disc baseplates, causing the baseplate tobe angled at a 15 degree lordosis angle, with the lower surface 164 a ofthe upper baseplate 168 a held against the upper surface 4200 g, and theupper surface of the shield being held against the lower surface 4200 h,as best shown in FIGS. 4a-e.

[0039] A knob 4120, threaded on the shaft 4020, can be rotated about thelongitudinal axis of the shaft 4020 to push the flange 4110 fartherproximally, to pull the pin 4090 tighter and therefore lock its position(the interference of the threads of the knob-shaft interface preventsthe knob 4120 from moving distally unless the knob 4120 is reverserotated to effect that result) to more securely hold the baseplate 168b, and reverse rotated to unlock and loosen the pin 4080.

[0040] When the disc 160 is held in this manner, rotation of the disc160 about a longitudinal axis (of the disc 160) relative to theinserter/impactor 4000 is prevented by interference of the corners ofthe disc's 160 flat surfaces (180 a-c and 180 d-f and the corners of theinserter/impactor's 4000 flat surfaces (4200 a-c and 4200 d-f, similarto the manner in which a wrench holding a nut prevents rotation of thenut relative to the wrench. Further, the holding of the disc 160 in thismanner allows for some repositioning of the disc 160 in theintervertebral space via rotation of the disc 160 in either directionabout the longitudinal axis of the intervertebral space. Further whenthe disc is held in this manner, rotation of the disc about a lateralaxis (of the disc 160) relative to the inserter/impactor 4000 isprevented by interference of the inwardly facing surface 164 a of thefirst baseplate (e.g., upper baseplate) of the disc and the uppersurface 4200 g of the wedge on the distal end 4040, and by interferenceof the inwardly facing surface 164 b of the second baseplate (e.g.,lower baseplate) of the disc and the lower surface 4200 h of the wedgeon the distal end 4040. Accordingly, the holding of the disc in thismanner allows for some repositioning of the disc in the intervertebralspace via rotation of the disc in either direction about thelongitudinal or latitudinal axis of the intervertebral space

[0041] In some embodiments, when the artificial intervertebral disc 160is held by the inserter/impactor 4000, the flat surfaces 180 a-c aremore closely confronted by the angled flat surfaces 4200 a-c of theinserter/impactor 4000, compared with the flat surfaces 180 d-f beingless closely confronted by the angled flat surfaces 4200 d-f of theinserter/impactor 4000. As such, the structure of the artificialintervertebral disc 160 having the flat surfaces 180 d-f (e.g., theupper baseplate 168 a) has slightly more rotation and angulation freedomrelative to the inserter/impactor 4000 when being held, compared to thestructure of the artificial intervertebral disc 160 having the flatsurfaces 180 a-c (e.g., the lower baseplate 168 b). This permits theartificial intervertebral disc 160 to adjust to the intervertebral space(e.g., to the angulation of the adjacent vertebral endplates, definingthe intervertebral space, relative to one another) as it is beinginserted thereinto. That is, typically, the adjacent vertebral endplateswill be lordotically angled with respect to one another as a result ofthe intervertebral space being prepared and distracted.

[0042] Preferably, in order to provide for a holding of the disc 160 fortwo additional (here, anteriolateral) insertion approaches, each disc160 also includes two additional holes 182 a and 182 c, one (e.g., 182a) spaced apart from one of the anteriolaterally facing flat surfaces(e.g. 180 a), and the other (e.g. 182 c) spaced apart from the other ofthe anteriolaterally facing flat surfaces (e.g. 180 c). Accordingly,operation of the inserter/impactor 4000 can fit the holding pin 4080into either of these two additional holes 182 a or 182 c, and hold theassociated anteriolaterally facing flat surface (the one associated withthe hole into which the pin 4080 is fit) of the disc 160 against theflat surface of the inserter/impactor 4000 opposite the pin 4080. Forexample, in a first anteriolateral approach for the disc 160, 180 a and180 d facing 4200 b and 4200 e, 180 c and 180 f not confronted, and 180b and 180 e facing 4200 c and 4200 f, and in a second anteriolateralapproach for the disc 160, 180 b and 180 e facing 4200 a and 4200 d, 180a and 180 d not confronted, and 180 c and 180 f facing 4200 b and 4200e. It should be understood that preferably, in order to facilitate theseadditional approaches, the angle separating the anteriorly facing flatsurface of the disc 160 and one of the anteriolaterally facing flatsurfaces of the disc 160 is equal to the angle separating the anteriorlyfacing flat surface and the other of the anteriolaterally facing flatsurfaces. Preferably, the surfaces are angled with respect to oneanother at an angle of 33.4 degrees.

[0043] It should also be understood that the inclusion of additionaladjacent angulated surfaces (or placing the angulated surfaces in otherlocations on the disc or other orthopedic device), and/or includingcorresponding holes adjacent to such surfaces, can provide the surgeonwith additional approaches, e.g., other anteriolateral approaches,directly lateral approaches, posteriolateral approaches, and/or directlyposterior approaches. For example, a trial or disc can have angledsurfaces (and corresponding holes) along the entire perimeter of one orboth of the baseplates, and thus enable the surgeon to engage the trialor disc from a number of angles, including anterior, posterior, lateral,anteriolateral, and posteriolateral angles.

[0044] The inserter/impactor 4000 further includes at a proximal end acap 4140 for use as an impact surface if the disc 160 must be impactedfurther into the intervertebral space after insertion, or forciblyextracted from the intervertebral space. A mallet can be used to strikethe cap 4140 (in a distal direction for impaction, or in a proximaldirection (using the flange of the cap 4140) for extraction). It shouldbe noted a striking of the cap 4140 will translate the striking force tothe baseplates through the shaft 4020 and the flat surfaces, but willnot damage the holding pin 4080 because the holding pin 4080 is springloaded in the central channel and thus buffered from the striking forcethereby. The distal end 4040 of the inserter/impactor 4000 furtherpreferably includes at least one vertebral body stop 4202 that protrudeslongitudinally with respect to the shaft 4020, from the surfaces of thedistal end. The stops help prevent the inserter/impactor from being usedto insert the disc (or other orthopedic device) too far into theintervertebral space.

[0045] Accordingly, the inserter/impactor 4000 can be used to grip theartificial intervertebral disc to be implanted, and hold the same duringinsertion and/or removal of the same, and is useful for a variety ofsurgical approach angles.

[0046] Now referring to FIGS. 5 and 6, a preferred embodiment ofinserter/impactor 4000 is described. In this embodiment at least onevertebral body stop 4202 has a ramped configuration, the ramp taperingfrom its peak adjacent the distal face of distal end 4040 toward theproximal end of inserter/impactor 4000. This configuration of the stop4202 assists in preventing the inserter/impactor 4000 from overinsertingthe disc (or other orthopedic device) into the intervertebral space andalso permits the inserter/impactor to 4000 to be employed in conjunctionwith the distractor shown in FIGS. 7-9, as described below.

[0047] As best seen in FIG. 6, in a preferred embodimentinserter/impactor 4000 is sized such that its thickness, excludingstop(s) 4202, is less than that of disc 160 so that the disk 160 has thelargest profile of any part introduced in the intervertebral space.Diminishing the profile of the inserter/impactor 4000 has the benefit ofminimizing the possibility of unintentional injury to the intervertebralspace, as well as permitting the inserter/impactor 4000 to be insertedbetween the wedge-ramps (described below) while holding the disc 160.

[0048] Now referring to FIGS. 7-9 a preferred embodiment of a distractoris disclosed. A distractor 5000 comprises essentially a pair ofidentical ramps 5100 facing one another and converging toward oneanother, and a connecting member (e.g., c-clip) 5200 having extensions(e.g., legs) 5210 for operably connecting ramps 5100 to each other. Theuse of multiple pieces eases cleaning of the distractor 5000 in anautoclave, and the use of the c-clip 5200 allows the ramps 5100 to bedoubly-hinged to one another for ease of extraction of the ramps 5100from the intervertebral space. In an alternate embodiment distractor5000 is formed as a unitary device. The distractor 5000 is sized tocorrespond to the baseplate footprint of the disc 160 that is to beimplanted, such that, preferably, the teeth 188 a,188 b (or othersuitable engagement features) of the disc 160 are able to travel in acorresponding guide feature (e.g., grooves 5118) in the ramps 5100 (asdescribed below).

[0049] Ramp 5100 has a connecting member receipt feature (e.g., channel)5110 disposed on its proximal end for receiving a leg 5210 of c-clip5200. The interior side 5130 of ramp 5100, i.e., the side that facesopposing ramp 5100, is defined by guide features (e.g., laterally spacedgrooves) 5118 disposed longitudinally on the interior side 5130 andextending along intervertebral space engagement members (e.g., laterallyspaced prongs) 5120 extending from the distal end of ramp 5100. Theexterior side 5140 of ramp 5100 is defined by vertebral body stopfeatures (e.g., transversely disposed ridges) 5142 formed at the base ofprongs 5120 adjacent the distal end of ramp 5100. An instrumentaccommodation feature (e.g., longitudinal aperture 5150) is formedmedially in ramp 5100 and, e.g., extends from the distal end of saidramp 5100 substantially parallel to grooves 5118 partially along thelength of ramp 5100.

[0050] C-clip 5200 further comprises a fastening device for securely butremovably engaging channel 5110, such as, but not limited to, a floatingball bearing 5122 that permits a leg 5120 of the c-clip to slidably andlockably engage channel 5110.

[0051] Now further referring to FIG. 9, as assembled, grooves 5118 ofthe respective ramps 5100 face one another. In this orientation,inserter/impactor 4000 (having the disc 160 mounted thereto) isinsertable between the opposing ramps 5100, with the teeth 188 a of theimplant base plates 168 a-b slidably engaging grooves 5118.

[0052] In practice, prongs 5120 are inserted between the vertebralendplates at the implantation site. Ridges 5142 prevent overinsertion ofthe prongs 5120 into the intervertebral space as the ridges 5142confront the anterior faces of the vertebral bodies. Once the prongs5120 are inserted, the disc 160, already secured to theinserter/impactor 4000, is placed onto the bottom ramp 5100 such thatthe teeth 188 a “ride” in the grooves 5118 as the disc 160 is pushedforward along the length of the bottom ramp 5100. The disc 160 ispreferably oriented such that the bottom base plate 168 b is parallel tothe ramp 5100 and the top base plate 168 a is held in a lordosedposition relative to the bottom base plate 168 b by theinserter/impactor 4000. Also, aperture 5150 accommodates the vertebralbody stops 4202 (having the ramped configuration) of a preferredembodiment of inserter/impactor 4000 (as shown in FIGS. 5-6) during theforward movement of the disc 160 and inserter/impactor 4000. (Thisconfiguration of the stop 4202 not only assists in preventing theinserter/impactor 4000 from overinserting the disc 160 (or otherorthopedic device) into the intervertebral space (by the confrontationof the distal end of the stops 4202 with the anterior faces of thevertebral endplates), but also permits the inserter/impactor to 4000 tobe easily withdrawn if it is necessary to remove or extract the disc 160prior to removing the ramps 5100 from the treatment site (as theinserter/impactor 4000 is pulled backwards between the ramps 5100, thetaper of the ramped proximal portion of the stop 4202 enables the stopto not catch on the proximal end of aperture 5150, but rather tosmoothly transition from the proximal end of aperture 5150 to theremaining proximal portion of the ramp 5100.)

[0053] Continued movement of the disc 160 toward the intervertebralspace is typically met with increased resistance as the space isdistracted (by the wedging action of the disc 160 being pushed forwardand thereby separating the prongs 5120) to accommodate the height of thedisc 160; manual pressure typically overcomes this resistance. Ifnecessary, a proximal flange 4140 on the inserter/impactor 4000 can bestruck to effect any additional force required. With regard to theconfiguration of the prongs 5120, the prongs 5120 are preferablydimensioned to facilitate guidance and passage of the disc 160 into theintervertebral space after leaving the distal portion of the ramps 5100past the ridges 5142, and out from the intervertebral space once thedisc 160 is disposed therein. More particularly, the prongs 5120 aredimensioned in width to slidably fit between the convex dome 184 a,184 band the teeth 188 a,188 b on the disc 160 baseplates, and dimensioned inlength to reach far enough into the intervetebral space to provideleverage support for the wedging action. Once the disc 160 is insertedinto the intervertebral space, the ramps 5100 are removed from theintervertebral space, preferably one at a time by first rotating the topramp 5100 out from between the disc 160 and the upper vertebral endplateusing the c-clip 5200 as a double-hinge. The bottom ramp 5100 may thenbe pulled out from between the disc 160 and the lower vertebralendplate. The inserter/impactor 4000 may then be removed from the disc160. Further with regard to the configuration of the prongs 5120, theprongs' 5120 dimensions preferably facilitate removal of the prongs 5120as the ramps 5100 are pulled out (i.e., the pulling out of the ramps5100 slides the prongs 5120 between the convex dome 184 a,184 b and theteeth 188 a,188 b of the disc 160, to avoid damage to the disc 160 orthe vertebral endplate.

[0054] It should be noted that the use of the prongs 5120 and thegrooves 5118 thereon, in which the teeth 188 a,188 b slide, avoids anypossible damage to the vertebral endplates as a result of engagement ofthe endplate by the teeth 188 a,188 b prior to full insertion of thedisc 160. That is, using the above-described method, the teeth 188 a,188b do not engage the endplate until after the prongs 5120 are removed,which is once the disc 160 is properly placed, and therefore the initialengagement of the endplate by the teeth 188 a,188 b is the finalengagement. Accordingly, because no gouging or scratching of theendplate by the teeth 188 a,188 b occurs, the teeth 188 a,188 b are lesslikely to move from their engaged position, which provides a more securefoothold for the disc 160.

[0055] Now referring to FIGS. 10 and 11, a preferred embodiment of adistractor 6000 is disclosed, comprising essentially a plying device6100 such as but not limited to a Beere-style distractor and a pair ofopposing forks 6200 adapted to engage therebetween an implant such as adisc 160.

[0056] Forks 6200 are adapted to connect to plying device 6100 using afastening device such as but not limited to a floating ball bearing 6202disposed on the proximal end 6210 of the fork 6200 to slidably andlockably engage a complementary portion 6102 of plying device 6100 suchas but not limited to a channel. Preferably a male/female couplingarrangement is provided. Collar 6204 is preferably employed to provide afirm engagement between plying device 6100 and fork 6200.

[0057] Fork 6200 is preferably configured to engage the intervertebralspace for distraction, while accommodating the passage of the disc 160between the forks 6200 while the space is held in distraction.Accordingly, to facilitate such passage while the space is held indistraction, the forks 6200 are offset from the primary longitudinalaxis of the plying device 6100, preferably as shown, such that theplying device can be operated to open the intervertebral space, but notobstruct a line of sight or an anterior insertion of the disc 160between the forks 6200 into the intervertebral space. More particularly,each fork 6200 comprises essentially an elongated portion 6220terminating in a substantially U-shaped member 6230 comprising a base6232 oriented substantially perpendicular to the elongated portion 6220and a pair of laterally spaced tines 6234 oriented substantiallyperpendicular to the base 6232. With regard to the offset nature of theforks 6200, is it preferable that one of the tines 6234 belongitudinally aligned with the elongated portion 6220. It is furtherpreferable that the base 6232 of the U-shaped member have a forwardridge surface perpendicular to the tines' outwardly facing surfaces,which ridge functions as a vertebral body stop to prevent the tines 6234from being inserted too deeply into the intevertebral space.

[0058] With regard to the ability of the disc 160 to pass into theintervertebral space, the U-shaped member 6230 and tines 6234 areconfigured to engage with or avoid certain features of the disc 160and/or an insertion tool (e.g., the inserter/impactor 4000). Forexample, the tines 6234 are preferably dimensioned to facilitateguidance and passage of the disc 160 into the intervertebral space, andout from the intervertebral space once the disc 160 is disposed therein.More particularly, the tines 6234 are dimensioned in width to slidablyfit between the convex dome 184 a,184 b and the teeth 188 a,188 b on thedisc 160 baseplates, and dimensioned in length to reach far enough intothe intervetebral space to provide leverage support for the distraction.Also particularly, the U-shaped member 6230 of fork 6200 has an interiorside (i.e., the side facing opposite fork 6200) defined by a notch 6240and curved profile 6300, which notch allows passage of the vertebralbody stops 4202 of the inserter/impactor 4000 as the disc 160 isinserted, and which curved profile permits passage of the convex dome184 a,184 b of the disc 160 as the disc is inserted.

[0059] In practice, the tines 6234 of forks 6200 of the distractor 6000are placed in an intervertebral space far enough that the forward ridgesurfaces of the base 6232 of the U-shaped member 6230 abut the anteriorfaces of the vertebral bodies. Next, the handles 6110 of plying device6100 are squeezed together to separate the tine pairs to urge thevertebral bodies apart and create an aperture for passage of the disc160 therethrough and into the intervertebral space. More particularly,in this position, the opposing interior sides of the U-shaped members6230 of forks 6200, by virtue of facing curved profiles 6300, arepositioned such that a disc 160, in a preferred embodiment alreadysecured to the inserter/impactor 4000, is positionable and translatablebetween the U-shaped members 6230. The curved profiles 6300 accommodatethe convex domes 184 a,184 b of the disc 160. Notches 6240 accommodatevertebral body stops 4202 of the inserter/impactor 4000. The width ofthe tines 6234 accommodate the teeth 188 a,188 b and convex dome 188a,188 b of baseplates 168 a-b for passage and guidance along the tines6234. Once the disc 160 is situated between the forks 6200, theinserter/impactor 4000 can be employed to manipulate the disc along thetines 6234. After insertion of the disc 160 in the intervertebral space,the distactor 600 is removed. and the inserter/impactor 4000 isdisengaged from the disc 160. Further with regard to the configurationof the tines 6234, the tines' 6234 dimensions preferably facilitateremoval of the tines 6234 as the forks 6200 are removed (i.e., thepulling out of the forks 6200 slides the tines 6234 between the convexdome 184 a,184 b and the teeth 188 a,188 b of the disc 160, to avoiddamage to the disc 160 or the vertebral endplate. Further preferably,the thickness of the extent of the tines 6234 is higher than the heightof the teeth 188 a,188 b rising off the baseplate surfaces. Accordingly,the use of tines 6234 of at least this thickness avoids any possibledamage to the vertebral endplates as a result of engagement of theendplate by the teeth 188 a,188 b prior to full insertion of the disc160. That is, using this insertion method, the teeth 188 a,188 b do notengage the endplate until after the tines 6234 are removed (thethickness of the tines 6234 prevents the teeth 188 a,188 b from engagingthe endplates), which is once the disc 160 is properly placed, andtherefore the initial engagement of the endplates by the teeth 188 a,188b is the final engagement. Accordingly, because no gouging or scratchingof the endplates by the teeth 188 a,188 b occurs, the teeth 188 a,188 bare less likely to move from their engaged position, which provides amore secure foothold for the disc 160.

[0060] While there has been described and illustrated specificembodiments of instrumentation, it will be apparent to those skilled inthe art that variations and modifications are possible without deviatingfrom the broad spirit and principle of the invention. The invention,therefore, shall not be limited to the specific embodiments discussedherein.

What is claimed is:
 1. An instrument for distracting an intervertebralspace, the instrument comprising: a first elongated section having aproximal end and a distal end, the distal end having at least two prongsextending therefrom for contacting a surface in an intervertebral space,and further having a proximal end and an interior side having at leasttwo laterally-spaced grooves disposed thereon; a second elongatedsection having a proximal end and a distal end, the distal end having atleast two prongs extending therefrom for contacting a surface in theintervertebral space, and further having a proximal end and an interiorside having at least two laterally-spaced grooves disposed thereon; saidfirst and second elongated sections connected at their proximal endssuch that said interior sides face each other, the interior sidesforming a passage dimensioned to accommodate the passage of anartificial intervertebral disc and a device for manipulating said disc,said passage effecting distraction of the intervertebral space.
 2. Theinstrument according to claim 1, each of said first and second elongatedsections comprising a curved cross section.
 3. The instrument accordingto claim 1 further comprising a device for releasably attaching saidelongated sections to each other at their respective proximal ends. 4.The instrument according to claim 1 further comprising a c-clip adaptedto releasably connect said elongated sections to each other at theirrespective proximal ends, each of said elongated sections furthercomprising a channel for receiving a leg of said c-clip.
 5. Theinstrument according to claim 1 at least one of said elongated sectionsfurther comprising an exterior side having at least one transverselydisposed ridge formed adjacent to the distal end of said elongatedsection.
 6. The instrument according to claim 1 at least one of saidelongated sections further comprising at least one longitudinal apertureformed medially thereon extending from the distal end of said elongatedsection.
 7. A method of distracting an intervertebral space comprisingthe steps of: providing an instrument comprising opposing rampedsurfaces having proximal and distal ends, said distal ends each havingat least one prong extending therefrom for contacting a surface in theintervertebral space, said first and second elongated sections connectedat their proximal ends such that interior sides of the elongatedsections face each other, the interior sides forming a passagedimensioned to accommodate the passage of an artificial intervertebraldisc and a manipulation device for manipulating said disc; insertingsaid prongs between the vertebral endplates defining the intervertebralspace; securing said disc to said manipulation device; inserting saidmanipulation device in said passage; advancing said manipulation devicethrough said passage such that the advancing manipulation device causesthe opposing ramps to spread thereby distracting said intervertebralspace.
 8. The method according to claim 7 comprising the further step ofinserting said disc into the intervertebral space.
 9. An instrument fordistracting an intervertebral space comprising: a pair of identicalramps facing one another and converging toward one another and aconnecting member operably connecting said ramps to each other, each ofsaid ramps further comprising at least two intervertebral spaceengagement members extending from a distal end of said ramp and aninterior side, said interior side comprising at least one longitudinallydisposed guide that extends along said intervertebral space engagementmembers.
 10. The instrument according to claim 9, said distractor sizedto correspond to a baseplate footprint of an artificial intervertebraldisc to be implanted.
 11. The instrument according to claim 9, said atleast one guides comprising at least two laterally-spaced grooves. 12.The instrument according to claim 9 said intervertebral space engagementmembers comprising laterally spaced prongs.
 13. The instrument accordingto claim 9 at least one of said ramps further comprising at least onevertebral body stop.
 14. The instrument according to claim 13 said atleast one vertebral body stop comprising a transversely disposed ridge.15. The instrument according to claim 9 further comprising an instrumentaccommodation feature formed medially in said ramp extending partiallyalong the length of said ramp.
 16. The instrument according to claim 9said instrument accommodation feature comprising a longitudinalaperture.
 17. A system for distracting an intervertebral spacecomprising: an instrument according to claim 9; an artificialintervertebral disc; and a manipulation device for manipulating saiddisc; wherein said artificial intervertebral disc comprising an upperbaseplate and a lower baseplate, each of said baseplates having outer,opposite facing surfaces, said outer surfaces having disposed thereon acentrally disposed convex dome and a plurality of teeth disposed alongat least a portion of a periphery of said baseplates, said vertebralspace engagement members dimensioned in width to slidably fit betweenthe convex dome and the teeth on the baseplates, and dimensioned inlength to reach far enough into the intervetebral space to provideleverage support for a wedging action.
 18. The system according to claim17 wherein the teeth of the disc are disposed such that they slidablyengage said longitudinally disposed guides.
 19. The system according toclaim 17 wherein the manipulation device is insertable between theopposing ramps.